JP5083783B2 - Apparatus and method for determining position match with reference position - Google Patents

Description

  The present invention relates to an apparatus and method for determining a position match or matching with a reference position and may be used, for example, specifically for positioning or navigating mobile terminals in a wireless communication network.

  Various positioning techniques are available to find people with mobile terminals. Probably the best known system for positioning and / or outdoor navigation is the satellite assisted positioning system (GPS). For positioning and / or navigation in buildings and / or indoor areas, such as field strength assessment of infrared systems, RFID (radio frequency identification) systems, or IEEE 802.11 wireless local area networks (WLANs). Various approaches are known. Currently, the GPS system is available as a reliable method only for outdoor areas. As more recent extensions, high-sensitivity receivers, so-called A-GPS (assisted GPS), etc., indicate attempts to create technologies that can be used in buildings. Here, A-GPS is a combination of a satellite-based GPS system and so-called assistance information reception from a portable wireless network. However, at present, these techniques do not provide the desired average accuracy. Infrared and RFID systems are generally not fully available and must meet special prerequisites.

  For example, with the increasing popularity of wireless radio networks based on the WLAN standard, these wireless networks serve as the basis for new positioning methods.

  In general, positioning methods that have been used so far include, for example, triangulation, neighborhood relations, and lateralization based on time measurement of lateralization using electric field strength evaluation. These methods require that the location of the fixed transmitter and / or base station must be known or whether training is performed in advance at typical locations in the area covered by the positioning method. This is a positioning method in which either is performed.

  In WLAN-based positioning systems, the so-called received signal strength (RSS) fingerprinting method is often employed as a basic method. This method is based on the assumption that the signal strength of the radio signals of several radio stations received and / or receivable at the current location uniquely characterizes the location or position. If there is a database for the identification of radio stations received and / or receivable there, as well as the field strength of the corresponding radio signal for a plurality of reference locations or reference locations, From the transmitter identification and signal strength values) can be estimated by performing a match between the currently measured measurement and the database reference value. For each reference point, this matching evaluates how similar that pre-recorded measurement and / or reference value is to the current measurement at the current location. The most similar reference point then estimates the current location.

  For the reference database, the signal strength is determined experimentally by test measurements at a sufficient number of points. Thereby, for each location where a test measurement has been performed, a list of base stations (access points) having an associated received field strength and quality is created. In a WLAN implementation, such a reference database may include parameters such as:

That is, the table contains the following information:
-Reference point identification (RID)
-MAC address of the receiving station-Received field strength of the access point (RSSI; 46560 means -46.560 dbm)
-Position in Cartesian metric coordinates (x, y, z; 24583 means 245.83 m), and
The time at which the measurements were captured WLAN signals should theoretically be measured only at relatively low field strengths, but relatively unreliable behavior with respect to “measurable” or “not measurable” Indicates. The PGS (percentage) column shows how many times this station has been seen in the period to capture measurements, in percent. (That is, PGS = 90 means that the station was measured 9 times on average in 10 measurements.) The PGS value is a reference position and / or reference measurement packet teaching for each wireless transmitter. And should be understood as an evaluation standard for its reliability. Within a certain measurement time frame, there is a defined number of possible measurements from the radio transmitter, for example with a fixed sampling interval of 200 ms. The PGS value is a percentage value of the radio transmitter (RSSI) value that was really measured within the measurement time frame with respect to the potential possible measurements. The reference position is captured, for example every 200 ms, over a longer time frame (eg 6 to 10 seconds) in the ideal case of a calibration period. In this regard, FIG. 5 shows an example of the received signal waveform of a particular radio transmitter, which can only be received with relatively low reliability at the measurement location. Over a measurement period of 10 seconds, that particular radio transmitter can only receive about 3 seconds, resulting in a PGS value of about 30% for this radio transmitter.

  For positioning, the currently captured measurements are compared with a database. The most similar reference value or the integral value of the most similar reference value is accepted as the current position. Various methods are possible for matching, and the most widely used is the least distance method in signal space.

  RSS fingerprinting gives good results in indoor and outdoor areas. Due to the fact that the location of the fixed radio transmitter does not need to be known, the method is also well suited for unknown environments with unknown infrastructure. The fingerprinting approach for matching assumes a fixed, immutable infrastructure. Many known solutions further assume a limited area where the signal of each wireless transmitter can be received anywhere.

  RSSI values for a plurality of wireless transmitters whose transmitter identification pre-recorded at the reference position is identical to the transmitter identification given at that position in order to determine a match or match of the current position using the reference position Are often compared to each other in a conventional manner. The smaller the RSSI value difference between wireless transmitters having the same transmitter identification, the higher the possibility of matching the current position with the reference position. However, this approach has the risk of incorrect position estimation, e.g. the number of radio transmitters for which the pre-recorded transmitter identification at the reference position is identical to the transmitter identification given at that position. If so, then the RSSI value difference is also judged to be small and may lead to good misestimated matches.

  Starting from this background, the object of the present invention is to provide a concept for the matching of currently measured values and pre-recorded reference values, which is improved with respect to the prior art.

  This object is achieved by a device having the features of claim 1, a navigation device according to claim 19 and a method according to claim 22.

  A further embodiment of the invention is a computer program for performing the method according to the invention.

  Considered the value and / or characteristics of a fixedly placed radio transmitter (eg, transmitter identification and signal strength value) currently given and / or measured at the current (geographic) location Matching between reference values and / or characteristics previously recorded at a (geographic) reference position is a characteristic of the radio signal currently measured at that position and a reference of the radio signal previously recorded at the reference position It is an outcome of the present invention that it can be achieved by a kind of filtering of values. Here, the radio signal is pre-recorded at the reference position with a first number of radio transmitters whose transmitter identification pre-recorded at the reference position is identical to the transmitter identification given at the current position. The transmitter identification and the transmitter identification given at the current location are divided into a second number of radio transmitters. That is, whether transmitter identification is given only at the current position and not pre-recorded at the reference position, or transmitter identification is pre-recorded only at the reference position and not given at the current position , Either.

  A set of measurements measured at the current location, including a transmitter identification (eg, MAC address) and associated signal strength value (RSSI) for wireless transmitter identification is: Is referred to as a measurement packet (MP). According to a preferred embodiment of the invention, the given measurement value at the current position and the measurement value previously recorded at the reference position are pre-filtered into three groups. On the other hand, all radio transmitters are separated from the measurement packets that are also included in the reference measurement packet inherent in the matching. A radio transmitter received at the current location and deviating (overheard) from the reference measurement packet implies that it cannot be at the reference location. These radio transmitters received in addition to the current position cannot be used in direct matching, ie matching between radio transmitters having the same transmitter identification in the current measurement packet and the reference measurement packet. Further, radio transmitters that were not received (not heard) at the current location may be listed in the reference data or reference measurement packet at the reference location. These radio transmitters and / or their measurements that were not received at the current location also require special processing and thus radio with direct matching, ie the same transmitter identification in the current measurement packet and the reference measurement packet Not supplied for matching between transmitters.

  The matching unit matches the current measurement at the current position with all reference points of the reference data in question. That is, the degree of matching between the current position and all the reference points in question is determined. The amount of matched reference points and / or positions takes the last position of the mobile terminal as a starting position, for example, and the user assumes that he has not moved from that last position beyond a fixed maximum distance since then Can be arbitrarily limited. The restriction of the reference points to be compared can be done dynamically depending on factors such as the movement model, the quality of the current position determination, the computing power limit or the memory limit.

  In each comparison between the reference measurement packet and the current measurement packet, the degree of matching is determined, which determines how well the measurement value received at the current position matches the pre-recorded reference position measurement value. . The determination of the degree of matching with respect to that position is made based on the given characteristics of the radio signal, and both the characteristics of the first number of radio transmitters and the characteristics of the second number of radio transmitters are matched. The characteristics of the first number of radio transmitters and the characteristics of the second number of radio transmitters are considered in the determination of the degree, and the degree of matching is input separately. For the first number of radio transmitters, the pre-recorded transmitter identification at that location matches the transmitter identification given at the current location. In the second number of radio transmitters, the transmitter identification is given only at the current position and not pre-recorded at the reference position, or pre-recorded only at the reference position and given at the current position. Or not.

  According to a preferred embodiment, the characteristics of the first number of radio transmitters are weighted more strongly than the characteristics of the second number of radio transmitters. This is because the number of transmitters whose pre-recorded transmitter identification at the reference position matches the transmitter identification given at that position is pre-recorded at the reference position in the calculation of the degree of matching. A second number of radio transmitters that differ from the transmitter identification and the transmitter identification given at that location, i.e. the transmitter identification was given only at that location and was not pre-recorded at the reference location, or This means that it is considered more strongly than the number of radio transmitters that are pre-recorded only at the reference position and are not given at the current position. The weights of the first and second number of characteristics, for example, complement the other complementarily.

Further preferred embodiments and further implementations are the subject of the dependent claims.
A radio transmitter whose transmitter identification is received only at the current position and not pre-recorded at the reference position, and which is pre-recorded only at the reference position and not received at the current position. By including, the determination accuracy of the degree of matching between the current position and the reference position can be remarkably increased. This can lead to significant improvements in positioning and / or navigation results.

  Preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

4 is a flowchart for illustrating a method of determining a match between a current position and a reference position according to an embodiment of the present invention. It is a figure which shows an example of a series of measurement packets. FIG. 3 is a schematic diagram of an apparatus for determining a match between a current position and a reference position according to an embodiment of the present invention. FIG. 4 is a block diagram of a means for determining a degree of position matching according to an embodiment of the present invention. It is a figure which shows the typical waveform of the radio transmitter which can be received with low reliability.

  With respect to the following description, the same or similar functional elements include the same reference numerals in different embodiments, and thus the descriptions of these functional elements are interchangeable with each other in the various embodiments illustrated below. It should be noted that there is.

  Next, based on FIGS. 1-4, the inventive concept for determining a match or matching between a current geographic location and a geographic reference location will be described.

  To obtain the reference position, the user records the wireless fingerprint as part of the database for use in subsequent positioning, for example, in the teaching phase. In practice, teaching can be performed using, for example, a PDA or a smartphone. The geographic map around the target is filed, for example, as a bitmap. In teaching, the user marks the current position on the map and starts capturing measurement values. In practice, it has been found that higher density teaching points obviously increase the amount of computation during positioning, but do not significantly improve the results.

  However, collecting fingerprints manually can only be performed within a limited area. In urban areas and urban centers, so-called calibration boxes can be employed for this purpose. These have a high-precision GPS unit (so-called differential GPS) in combination with a high-precision inertial sensor (for example, an acceleration sensor and an electronic compass). These calibration boxes can collect fingerprints without manual intervention when moving through cities and urban areas. Positioning via differential GPS continues for up to 20 minutes for position determination, even if the GPS system fails, but enables high accuracy inertia sensor technology with an average accuracy of tens of centimeters even in urban environments. Thus, for example, a road covered with a roof does not cause any problems for the calibration box.

  FIG. 1 is a flowchart for illustrating a method for determining whether the current position of a mobile terminal matches a reference position.

  The method for recognizing a match schematically illustrated in FIG. 1 comprises a first step S1 for recognizing and / or providing a characteristic of a radio signal of a fixedly arranged radio transmitter at a current position, and determining and / or The characteristics of the provided wireless signal include a transmitter identification that identifies the wireless transmitter. This therefore means in particular that the transmitter identification of the radio transmitter is recognized in step S1. Further, in a preferred embodiment of the present invention, the received signal strength, received power spectrum, signal-noise power ratio (SNR: S / N ratio), incident angle, propagation time, polarization or phase location of the radio signal The electromagnetic characteristics of the radio signal, such as location), are recognized.

In a second step S2, the radio signal and / or the radio transmitter associated with the radio signal is such that the transmitter identification pre-recorded at the reference position is identical to the transmitter identification given at the current position. Separation and separation into a number N _eq of radio transmitters of 1 and a second number of radio transmitters of N _neq in which the transmitter identification pre-recorded at the reference position differs from the transmitter identification given at the current position And / or filtered. That is, whether transmitter identification is given only at the current position and not pre-recorded at the reference position, or transmitter identification is pre-recorded only at the reference position and not given at the current position , Either. According to an embodiment, the second step S2 further comprises a pre-recorded characteristic at the reference position, ie a radio transmitter that was not received at the current position from the second number N _neq of radio transmitters. Includes a sub-step for selecting the number N _nh of radio transmitters without the given characteristics at the current location. The larger the number N _nh of radio transmitters not received at the current position, the less likely the current position corresponds to the reference position. Furthermore, step S2 includes further substeps, in which there is no previously recognized electromagnetic characteristic at the reference position, but there is an electromagnetic characteristic given at the current position, which is added at the current position. The number N _htm of wireless transmitters received at is selected from the second number N _neq . The larger the number N _htm of additional wireless transmitters received at the current position, the less likely the current position corresponds to the reference position. Therefore, the second number N _neq of radio transmitters is calculated from the number N _nh of radio transmitters not received at the current position and the number N _htm of additional radio transmitters received at the current position, N _neq = ( N _nh + N _htm ).

Based on the characteristics of the radio signal given from step S1, the degree of matching and / or the distance value acc for the current position is determined in a third step S3 and the characteristics of the first number N _eq of radio transmitters. And the characteristics of the second number N _neq of the radio transmitter are considered in determining the degree of matching, and the characteristics of the first number N _eq of the radio transmitter and the second number N _neq of the radio transmission As the characteristics of the machine, the degree of matching is input separately. According to the embodiment, the characteristics of the radio transmitter of the first number N _eq are weighted more strongly than the characteristic of the radio transmitter of the second number number N _neq, handled in detail below.

  According to the implementation mobile of the present invention, the step S1 of recognizing and / or providing the characteristics of the radio signal is for example a mobile terminal such as a WLAN-enabled PDA, a Bluetooth-enabled PDA or a mobile phone and / or Executed by the client. In order to achieve this objective, the client comprises means for qualifying and / or providing a radio signal characteristic of a fixedly arranged radio transmitter, which characteristic is generally the identification of the fixedly arranged radio transmitter. And characterized by electromagnetic signal characteristics such as received field strength, received spectrum or received S / N ratio. Identifying and / or identifying the characteristics of a fixedly located wireless transmitter can be, for example, a media access control (MAC) address, a base station identification, or a cell identification.

  The characteristics of the radio signal of the fixedly arranged radio transmitter are combined with a so-called measurement packet MP (i). This fact is illustrated in FIG.

FIG. 2 illustrates three temporally continuous measurement packets MP (1), MP (2), MP (3) from the WLAN network, i = 1,2,3. MP (i) includes a plurality of MAC addresses 22 and associated RSSI values, RSSI _k (i), and index k indicates the kth radio transmitter. This means that the MAC addresses of the fixedly arranged radio transmitters and their RSSI values received by the client are combined into the measurement packet MP (i) every time interval.

  FIG. 3 shows an apparatus 30 for determining a match between a current position and a reference position according to an embodiment of the present invention. Here, a fixedly located radio transmitter and / or base station may be received at the current location.

In order to achieve this object, the device 30 comprises means 32 for providing the radio signal characteristics of a radio transmitter fixedly located at the current position, the provided radio signal characteristics comprising: Includes transmitter identification, such as an identifying MAC address. In order to achieve this purpose, the means 32 can be coupled with a receiving antenna 33 for receiving the characteristics of a radio signal, such as electromagnetic characteristics. In fact, the previously described measurement packet MP (i) can be implied by the characteristics of the radio signal. The certified and / or provided measurement packet MP (i) is used to transmit radio signals and / or radio transmitters associated therewith to a first number N _eq of radio transmitters and a second number of N _neq radios. Is provided to means 34 for separating from the transmitter. Here, the first number N _eq of radio transmitters includes radio transmitters whose transmitter identification pre-recorded at the considered reference position matches the transmitter identification determined at the current position. The second number N _neq = (N _nh + N _htm ) radio transmitters have transmitter identification given only at that location and not pre-recorded at the reference location, or pre-recorded only at the reference location and Includes any radio transmitter that is not given at that location. To determine the radio transmitter and the radio transmitter of the second number N _neq first number N _eq, means 34 for separating the pre-recorded radio signals from a plurality of reference position characteristic That is, it can be combined with the database 35 in which the reference measurement packet is stored. This means that the database 35 contains, for example, various pre-recorded measurement packets, each associated with a reference position. These pre-recorded measurement packets are then to be referred to as reference measurement packets RP. Accordingly, the means 34 separates the radio signal into two groups. The first group 36 includes the characteristics of the radio signals of the first number N _eq of radio transmitters, while the second groups 37, 38 include the radio signals of the radio signals of the second number N _neq of the radio transmitters. Includes characteristics. As already mentioned above, the second group 37, 38 consists of a group of radio signal characteristics of radio transmitters not received at the current position and radio signals from radio transmitters additionally received at that position. It can be further subdivided into groups of characteristics 38.

The apparatus 30 further includes means 39 for determining the degree of matching with respect to the current position, which can be coupled to both the means 34 for separating and the database 35. The means 39 is configured to determine the degree of matching based on the given characteristics 36, 37, 38 of the radio signal, and the radio signal characteristics 36 and second of the first number N _eq of radio transmitters. The radio signal characteristics 37, 38 of the number N _neq of radio transmitters are taken into account in determining the degree of matching and / or the distance value acc, and the radio signal characteristics 36 of the first number Neq of radio transmitters and The radio signal characteristics 37, 38 of the number N _neq radio transmitters of 2 are input separately, ie weighted separately, to the degree of matching.

  Means 32 provides various base station and / or radio transmitter signals of different signal strengths, along with associated transmitter identification, at any location and / or at any location. For WLAN networks, such electronic fingerprints include a list of unique MAC addresses for each WLAN device and / or WLAN radio transmitter and their associated received signal strength, thereby characterizing the current location . It doesn't matter where the radio transmitter is.

  Positioning consists essentially of two steps. The first is a match between the currently measured measurement packet and the fingerprint and / or reference measurement packet in the database 35, and the second is the selection of suitable location candidates, as well as the other Weighting and combining candidate positions to estimated positions.

  In the matching phase, a deviation between the currently measured measurement packet MP (i) and the reference measurement packet RP in the database 35 is determined. In fact, the means 34 and 39 of the device 30 according to the invention serve this purpose.

  In order to find possible candidate positions for the current position from the various reference positions stored in the matching phase, the means 39 measures the currently measured measurement packet and the reference measurement packet previously recorded at the reference position. The degree of matching between and is determined. A schematic block circuit diagram of the means 39 for determining the degree of matching and / or the distance value acc is shown in FIG.

As already mentioned above, the means 39 are supplied on the input side with an electromagnetic characteristic 36 of the first number N _eq of radio transmitters, for example an RSSI value. In addition, a second number N _neq of radio transmitter electromagnetic characteristics 37, 38, such as RSSI values, appear at the input of the means 39. Here, the characteristics 36 of the first number N _eq of radio transmitters include both signal characteristics measured at the current position and signal characteristics previously recorded at the reference position.

According to an embodiment, at block 41, a difference is formed between the pre-recorded signal characteristic at the reference position and the electromagnetic characteristic provided at the current position of the first number N _eq of radio transmitters. For example, a difference in the RSSI value of the wireless transmitter is formed in which the transmitter identification pre-recorded at the reference position matches the transmitter identification given at the current position. These RSSI value deviations ΔRSSI ₁ to ΔRSSI _Neq are given to the addition block 42, which adds N _eq RSSI value deviations ΔRRSI _n (n = 1,... N _eq ) to give a total value ΣΔRSSI. _n is calculated. N _eq is the first number N _eq of radio transmitters in both the measurement packet and the reference packet. The function ΔRSSI calculates the distance between two signal strength values. The Euclidean distance of the measured value in decibels (db) can be selected as a distance function, for example. In this connection, therefore, distance does not mean a spatial distance, but a mathematical deviation. Subsequent to the addition by block 42, the total value ΣRSSI _n is weighted using a weighting factor EQW, ie EQW · ΣRSSI _n . Here, EQW defines a weight between 0 and 1, and the distance of the measured value and / or the distance of the signal strength value ΣΔRSSI _n is too audible or almost compared to the radio transmitter at the current position It shows how strong and important it is about not being heard.

If the calculation of the degree of matching is stopped at this time, a reference position that does not actually match well may be selected as a candidate rather than a reference position that is more suitable for the current position. As an example of this, if N _neq = 1 is obtained for the first reference position compared to the current position, ie only one radio transmitter identification is present between the reference measurement packet and the current measurement packet. Assume that there is a match. If the corresponding RSSI values of the measurement packets that match by chance are, for example, 2.5 dB apart, ΣΔRSSI ₁ / N _neq = 2.5 dB is obtained. Furthermore, if the result of N _neq = 3 is obtained for the second reference position compared to the current position, ie, the three radio transmitter identifications match between the reference measurement packet and the current measurement packet. Assume. For example, if the corresponding RSSI values are 2 dB, 3 dB, and 4 dB apart, ΣΔRSSI _n / N _eq = 3 dB is obtained as a whole. As a result, the second reference point is evaluated as worse than the first reference point, which leaves an estimation error. Embodiments of the present invention may prevent and / or at least reduce such estimation errors.

Reference number 37 is _derived from N _nh number of radio transmitters that were not received at the current position, ie, radio transmitters that have pre-recorded characteristics at the reference position but no characteristics given at that position, ie Characterize the characteristics of radio signals from radio transmitters that cannot be received at the current location. In block 43, a Malus function and / or a Malus value M _{nh, m} () (m = 1,..., N _nh ) may be defined for each radio transmitter that was not received. This means that the Malus value M _{nh, m} () (m = 1,..., N _nh ) can be defined for each station that is within the reference value but not within the current measurement. This may depend, for example, on how reliably a corresponding station that was not received in the past could be received at the reference location. In the case of a previous good reception capability of a station that was not received, i.e. a high RSSI value, for example, a high malus value results. Thus, according to an embodiment, the malus value M _{nh, m} () (m = 1,..., N _nh ) may be directly proportional to the reference RSSI value of the station that was not received at the current location. Furthermore, the Malus function M _{nh, m} () (m = 1,..., N _nh ) may be combined with the corresponding PGS value of the wireless transmitter that was not received. A small PGS value in the reference database can, for example, only lead to a small value of the corresponding malus value M _{nh, m} () (m = 1,..., N _nh ). This can be calculated, for example, by the following equation: M _{nh, m} (PGS) = fixed malus + dynamic malus. Here, dynamic malus = fixed malus * PGS / 100. Therefore, according to an embodiment, the function M _{nh, m} () (m = 1,..., N _nh ) for the malus value for a radio transmitter that was not received is a characteristic related to the received field strength, and As with the model, it depends on pre-recorded characteristics at a reference point such as the environment and the quality of the measured values. Mnh Malus values M _{nh, m} () (m = 1,..., N _nh ) for radio transmitters not received at the current location are passed to block 44 for the radio transmitters not received. A first total value ΣM _{nh, m} () of M _nh malus values is determined.

The characteristic of the radio signal from the N _htm radio transmitters additionally received at the current position is given by reference numeral 38. What is meant by this is a radio transmitter in which there is no pre-recorded electromagnetic characteristic at the reference position, but there is an electromagnetic characteristic given at the current position. In block 45, the Malus function M _{htm, r} () (r = 1,..., N _htm ) and / or the Malus value may be associated with each of the additionally received radio transmitters at the current location. This is not found at the reference position, but for a radio transmitter included in the current measurement, the malus value M _{htm, r} () (r = 1,..., N _htm ) can be defined. means. Here, the function for the malus value M _{htm, r} () (r = 1,..., N _htm ) is similar to that of the model, for example, the environment, the quality of the measured value, the age of the reference data, etc. It also depends on current RSSI measurements. According to one embodiment of the present invention, this is because the means 39 for determining the radio in which the malus value M _{htm, r} () (r = 1,..., N _htm ) is additionally received at the current position. It is formed to be associated with the transmitter and means that it depends on characteristics related to the received field strength of the radio signal, for example the RSSI value. Thus, according to the embodiment, the malus value M _{htm, r} () (r = 1,..., N _htm ) is directly proportional to the reference RSSI value of the station additionally received at the current position. Further, the Malus function M _{htm, r} () (r = 1,..., N _htm ) may be combined with the corresponding received PGS value of the wireless transmitter. For example, a smaller PGS value in the reference database may lead to a smaller value of the corresponding malus function M _{htm, r} () (r = 1,..., N _htm ).

The additionally received N _htm malus values of the radio transmitter are transferred to the addition block 46, and the N _htm malus values are added to form a second total value ΣM _{htm, r} ().

According to the embodiment, the first total value ΣM _{nh, m} () of the malus value of the radio transmitter that was not received and the second total value ΣM _{htm, r} () of the radio transmitter that was additionally received. Are added and weighted with a weighting factor (1-EQW). That is, (1−EQW) · (ΣM _{htm, r} () + ΣM _{nh, m} ()).

Finally, according to an embodiment, a weighted sum of the differences between the electromagnetic characteristics pre-recorded at the reference position and the electromagnetic characteristics given at that position of the first number Neq of radio transmitters The value EQW · ΣΔRSSI _n and the weighted total value (1-EQW) · (ΣM _{htm, r} () + ΣM _{nh, m} ()) of the malus value are normalized by (N _eq + M _nh + N _htm ) A distance value acc between the current position and the considered reference position is obtained. The distance value acc is, for example,

Calculated according to
If the distance value acc is determined according to equation (1), the greater the match between the current position and the considered reference position, the smaller the distance value acc. This means that the greater the match, the smaller the total difference value ΣRSSI _n and the smaller the total value ΣM _{nh, m} (), ΣN _{htm, r} () of the malus value. According to the embodiment, the distance value acc corresponds to the degree of matching.

According to other embodiments, the degree of matching can be the reciprocal of the distance value acc, or can be calculated by (1-acc) if acc is never greater than 1. . This means that the smaller the distance acc, the greater the degree of matching. Of course, other laws of calculation are possible as well, the characteristics of the first number N _eq of the radio transmitter and the characteristics of the second number N _neq = (N _nh + N _htm ) of the radio Enter the degree separately.

  In an embodiment of the invention, therefore, each additionally received or not received station increases the distance acc. The processing of different stations in the fingerprint and current measurement affects the accuracy. That is, a station that is not found in the stored reference fingerprint but appears in the current measurement gives a strong indication of the fact that this fingerprint is not suitable.

  In a large area, the distance calculation for all stored reference fingerprints according to equation (1) can be time consuming. Therefore, pre-selection of the reference fingerprint is advantageous. The terminal's final calculated position may already give an indication of the current position. The surrounding digital map may further limit the number of candidates. However, such area restrictions also pose a danger. If the estimated position is misplaced, the positioning can no longer be recovered and stuck at its “worst” position. That is, it is also always a problem of checking the absolute quality of candidate positions. For example, if the absolute quality of the best candidate is too bad due to a very weak RSSI value, matching should be restarted without using region restrictions. At the end of the matching phase, a plurality of possible locations and / or candidate positions are obtained from the estimates that could be determined for the current position.

  The best position candidate determined in the matching phase is adopted for the so-called position calculation phase in a navigation device including the device 30 according to the invention. To achieve this objective, the navigation device according to the invention further comprises means for outputting an estimate for the current position based on the degree of matching and / or the distance acc communicated by the device 30.

  Means for outputting an estimate for the location calculates a location of the mobile terminal and / or an estimate of the location from candidate locations that are not higher or lower than a default limit for the degree of matching and / or the distance acc. . Here, the individual positions are not considered much, but rather are arranged in the context of the overall movement. The result represents an estimate of the current location of the terminal.

  A simple implementation is, for example, calculation of a weighted average value of candidate positions. The value depends on the degree of matching of candidate positions, for example, the reciprocal of the degree of matching, where the weights of candidate positions are formed in the averaging. This so-called k-weighted nearest neighbor method gives very reasonable results. The average positioning error is a few meters.

  However, the estimation of the current position can also be determined by more complicated methods, for example, probability calculations such as Bayesian methods or Markov chains. Here, the basic idea is to compensate for errors in individual position estimation by considering and optimizing the entire path thereafter. The most likely route calculation may further include additional data such as a surrounding map. A motion estimation filter such as a Kalman filter may also be employed. Such a filter estimates the direction of motion, velocity and acceleration based on the final position and establishes future predictions. Matching between predictions and estimated positions can recognize and correct unbelievable movements and jumps.

  In the matching and location calculation phase, the surrounding digital map can provide important additional information. A digital surrounding map that can see possible paths helps to recognize impossible movements and correct impossible movements to possible paths. Thereby, the positioning accuracy can be significantly increased. The digital map consists of possible paths (active maps) that contain only inaccessible areas (negative maps) or represent structural states (real maps) such as floors, walls or doors It can be either. In the field of vehicle navigation, it is customary to employ a positive map. These include not only roads and routes, but also important metadata (eg driving directions and speed limits on one-way roads). A positive map makes sense here because accessible roads and routes occupy only a small part of the land.

  However, in buildings, halls, or factory premises, the route is only limited by a few obstacles. Here, a negative map or a real map is obvious. Positive maps for vehicle navigation are commercially available in several standard formats (such as GDF, SIF or ArcView), but for maps in and around buildings, the standard is currently under development It has not been. Previous WLAN positioning methods leave the user to establish a map of the surroundings in the appropriate format and provide assistance as a dedicated tool. Basic information can often be obtained from bitmaps or CAD diagrams. Therefore, the development of 3D (3D) maps suitable for town or city and national navigation, including street and public buildings as well as building details, is an important step towards standardizing the map format. is there.

  In summary, it is pointed out that, depending on the situation, the concept of the present invention is also implemented in software. An example implementation is a digital storage medium with electronically readable control signals that can cooperate with a programmable computer system and / or microcontroller such that the corresponding method can be performed, specifically a floppy disk, CD or It can be a DVD. Accordingly, in general, the present invention is a computer program having program code stored on a machine-readable carrier for performing the method of the present invention when executed on a computer and / or microcontroller. It is also a product. Thus, in other words, the present invention may be implemented as a computer program having program code for executing the method when executed on a computer and / or microcontroller.

Claims (20)

A equipment for determining a coincidence of the position of the reference position, the radio signals from the fixedly positioned radio transmitters are received at the location,
In said position, a manual stage for providing the characteristics of the radio signals of the fixedly positioned radio transmitters, characteristic of a given said radio signal, the transmitter identification for identifying said wireless transmitter The apparatus further comprises:
Free line transmitter, a first number of radio transmitters transmitter identifications previously recorded at the reference position is identical to the transmitter identifications provided at the position, and pre-recorded in said reference position a manual stage for separating the transmitter identification and the transmitter identification is different second number of radio transmitters given in position, said means for separation is hardly received in said position, Multiple radio transmitters that have pre-recorded characteristics at the reference position but no characteristics at the position, or that are additionally received at the position and no pre-recorded electromagnetic characteristics at the reference position Wherein the device is configured to select a plurality of radio transmitters from the second number of radio transmitters, wherein the device has an electromagnetic characteristic provided at the location ;
Based on the given characteristics of the radio signal, a manual stage for determining the degree of matching for the position, the second number characteristics Contact and radio transmitters of the first number both the wireless transmitter characteristics are taken into account in determining the degree of matching, characteristics before Symbol properties of the first number of radio transmitters and said second number of radio transmitters, the degree of the matching The means for separately determining and determining is configured to associate a malus value with one of the radio transmitters not received at the location, or additionally received radio at the location. A device configured to associate a malus value with a transmitter . Said second number of radio transmitters, transmitter identification which has not been recorded previously only in given and the reference position in said position, or, e given in by and the location recorded in advance only at the reference position It is not been a transmitter identification device of claim 1. The first characteristic of the wireless transmitter number, the second is the number of radio transmitters strongly weighted characteristics by remote The apparatus of claim 1 or 2. The characteristics of the wireless signal comprises an electromagnetic properties of the radio signals, according to claim 1. Hand stage for the determination, based on the difference between the electromagnetic properties given in electromagnetic characteristics and the position recorded beforehand have you to the reference position of the radio transmitters of the first number 5. The apparatus of claim 4, wherein the apparatus is configured to determine a degree of the matching for the location. Hand stage for the determination, as the total of the difference is smaller, is formed so as to be associated with the degree of a higher matching its position, according to claim 5. Hand stage for providing the characteristics of the radio signal, the at the location is formed to provide the associated properties to the reception field strength of the radio signal, apparatus according to any one of claims 1 to 6 . Hand stage for providing the characteristics of the radio signal, in said position, RSSI value of the radio signal is formed to provide the received power spectrum or signal noise power ratio, Apparatus according to claim 7. Hand stage for the determination, form said wireless transmitter depending on whether could be received How reliably in the past at the reference position, to associate the malus value to a radio transmitter that is hardly received in said position The device according to any one of claims 1 to 8, wherein: Hand stage for the determination, depending on the characteristics associated with the received signal strength, is formed to associate the malus value to a radio transmitter which is not received at the position, one of the preceding claims 1 The device according to item . Hand stage for the determination, as the total of the malus values of the radio transmitters not received at said position is smaller, it is formed to associate the location with a degree higher matching claim 1 The apparatus according to any one of 10 . Hand stage for the determination, depending on the characteristics associated with the received field strength of the wireless signal, the wireless transmitter received in addition at the position, is formed to associate the malus value, apparatus according to any one of claims 1 to 11. Hand stage for the determination, the sum of the malus values of the radio transmitters received in addition at the positions as smaller, is formed to associate the location with a degree higher matching claim The apparatus according to any one of 1 to 12 . Hand stage because given the characteristics of the radio signal, WLAN (wireless local area network) is formed so as to determine a characteristic of the radio signal, apparatus according to any one of claims 1 to 12. A navigation device,
According to any one of claims 1 to 14, and the equipment for determining the degree of matching between the reference position and the current position,
And a means for outputting an estimate of the current position based on the determined degree of matching. Equipment for determining the degree of the matching between the reference position of the limited current location number, is formed so as to form the degree of each matching,
The navigation device according to claim 15 , wherein the limited number of reference positions is in a predetermined neighborhood of an estimate of a previous position relative to the current position. The means for outputting the estimated value is configured to determine and output the estimated value based on an average value of a plurality of reference positions having a degree of matching above or below a limit value. The navigation device according to claim 15 or 16 . A method for determining a position match with a reference position, wherein a radio signal from a fixedly arranged radio transmitter is received at the position,
In said position, the characteristics of the includes a fixedly positioned the step of providing the characteristics of radio signals of the radio transmitters, said given wireless signals include transmitter identification for identifying the wireless transmitter, The method further comprises:
Free line transmitter, a first number of radio transmitters transmitter identifications previously recorded at the reference position is identical to the transmitter identifications provided at the position, and pre-recorded in said reference position Separating into a second number of radio transmitters having different transmitter identifications and transmitter identifications given at the location, the separating step being received little at the location and pre- Multiple radio transmitters with recorded characteristics but no characteristics at the position, or additionally received at the position and no pre-recorded electromagnetic characteristics at the reference position, but given at the position Selecting a plurality of radio transmitters from the second number of radio transmitters, wherein the method is further characterized in that the method further comprises:
Wherein based on the given characteristics of radio signals, and determining the degree of matching for the position, the first number of radio transmitters characteristics Contact and said second number of radio both characteristics of the transmitter is considered in determining the degree of matching, characteristics before Symbol properties of the first number of radio transmitters and said second number of radio transmitters, separately degree of the matching And the malus value is associated with one of the radio transmitters not received at the location, or a radio transmitter additionally received at the location . A computer program having program code executed on a computer for executing the position identifying method according to claim 18 . An apparatus for determining a match between the current position and a reference position based on a radio signal received at a current position from a fixedly arranged radio transmitter,
Means for determining a characteristic at the current position of the radio signal of the fixedly arranged radio transmitter, wherein the determined characteristic of the radio signal is a transmitter identification for identifying the radio transmitter; The apparatus further comprises:
Means for separating the fixedly arranged radio transmitters into a first number of radio transmitters and a second number of radio transmitters, wherein the first number of radio transmitters comprises the reference position; Including a fixedly located radio transmitter whose pre-recorded transmitter identification is the same as the transmitter identification determined at the current location, wherein the second number of radio transmitters is pre- The transmitter identification recorded in the current position and the transmitter identification determined at the current location are differently arranged, the means for separating from the second number of radio transmitters, (I) a plurality of radio transmitters with pre-recorded characteristics at the reference position but no characteristics determined at the current position, or (ii) no characteristics pre-recorded at the reference position The current Characteristics determined in location is formed so as to select a plurality of radio transmitters, the in, the apparatus further comprises
Means for determining a degree of matching for the current location based on the determined characteristics of the radio signal, the determination of the degree of matching comprising characteristics of the first number of radio transmitters and Based on the characteristics of the second number of radio transmitters, the characteristics of the first number of radio transmitters and the characteristics of the second number of radio transmitters being weighted differently, the matching Means for determining the degree of: (i) one of the fixedly located radio transmitters not received at the current location, or (ii) received at the reference location and pre- An apparatus configured to associate a malus value with a wireless transmitter that has no recorded characteristics, but has a characteristic determined at the current location.

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